Level and Flatten a Floor Surface

A. Finished-Project Specification

Quantity: one defined correction area, with every marked high spot and low area corrected to within the manufacturer-specified flatness tolerance, measured using the specified straightedge length, and reverified after the specified cure time.

B. Flatness Correction Schedule

Item	Target Condition	Verification Method
Manufacturer tolerance	Correct straightedge length and permitted deviation confirmed before measuring	Written record on the Flatness Correction Record
Flatness survey	Straightedge placed across multiple directions; every high spot and low area marked	Straightedge and feeler-gauge measurement
Wood-substrate correction	Minor ridges planed or sanded without reducing panel thickness below the permitted limit	Depth measurement and visual inspection
Concrete-substrate correction	Irregularities ground or scarified only after silica and hazardous-material controls are confirmed	Visual inspection and control-plan record
Patch or leveling application	Primer and compound mixed and applied within the specified ratio, working time, and depth	Batch record and depth check during application
Cure protection	Repair protected from traffic and moisture through the specified cure period	Elapsed-time record and visual inspection
Reverification	Flatness rechecked at the same marked points using the same straightedge and method	Straightedge and feeler-gauge measurement

C. Material Takeoff

• Patch or self-leveling compound: quantity sufficient to cover the marked low areas at the depth specified by the manufacturer, plus the manufacturer's stated waste allowance.
• Primer: quantity sufficient for the full correction area at the coverage rate stated on the product label.
• Abrasives: sanding discs or belts, or approved grinding wheels, matched to the substrate and sufficient for the marked high-spot area.
• Marking supplies: chalk or marking tape sufficient to flag every high spot, low area, and reverification point.
• Documentation: one Flatness Correction Record per correction area, plus photographs of marked deviations, correction in progress, and final readings.

D. Product and Application Schedule

Application	Product	Mixing/Ratio	Depth or Coverage	Cure Time
Primer	Manufacturer-specified primer identified for the substrate and patch product	Per manufacturer instructions	Per manufacturer coverage rate	Per manufacturer instructions before patch application
Floor patch or self-leveling compound	Manufacturer-specified product identified for the substrate and flooring system	Per manufacturer water ratio and mixing time	Per manufacturer maximum and minimum depth	Per manufacturer instructions before reverification and before underlayment

Do not substitute a different product, water ratio, application depth, or cure time than the one identified by the flooring manufacturer for the substrate and flooring system in use. Where a value is not supplied by the manufacturer's instructions, do not invent it — stop and obtain the manufacturer's written specification before proceeding.

E. Acceptance Standards

Check	Standard
Flatness	Every marked point measures within the manufacturer-specified tolerance for the specified straightedge length
Wood-panel thickness	No sanded or planed area reduced below the manufacturer- or code-permitted panel thickness
Dust control	No visible dust residue remaining before priming or patching; HEPA vacuuming completed and documented
Patch application	Patch or leveling compound applied within its stated working time, at the specified depth, without bridging active cracks or movement joints
Cure	Full manufacturer-specified cure time elapsed before reverification or underlayment installation
Reverification	Same straightedge length and method used to recheck every originally marked point
Documentation	Flatness Correction Record complete with product, batch, depth, cure, and final readings

F. Confirm Requirements and Prior Conditions

1. Review the flooring manufacturer's flatness requirement and approved patching or grinding products. Record the required straightedge length, permitted deviation, and identified product names on the Flatness Correction Record.
2. Confirm that structural movement, loose panels, cracks requiring engineering, and moisture problems are resolved. Verify against the Project 01 Flooring-Readiness Plan and the Project 03 structural-repair record before proceeding.

G. Clean and Survey the Substrate

1. Clean the substrate completely. Remove debris, dust, adhesive residue, and loose material before any measurement begins.
2. Place the specified straightedge or use the approved survey method across multiple directions. Cover the full correction area, including areas near walls and transitions.
3. Mark high spots, low areas, abrupt ridges, seams, and transitions. Use chalk or marking tape at every point where the measured gap approaches or exceeds the manufacturer's tolerance.
4. Record the largest measured deviation. State its exact location on the Flatness Correction Record before beginning any correction.
5. Distinguish isolated ridges from broad elevation changes. Identify whether each marked point requires sanding or planing, patch, self-leveling compound, or grinding based on its shape and extent.

H. Correct Wood-Substrate High Spots

1. For wood substrates, tighten or repair panels before surface correction. Confirm any remaining fastening or panel-seam issue is corrected under Project 03 methods before sanding or planing.
2. Plane or sand minor wood ridges using dust extraction and approved depth control. Operate the sander or plane with dust extraction connected and check depth against the marked deviation as work proceeds.
3. Do not reduce structural panel thickness below the permitted limit. Stop correction at a marked point if continued removal would reduce the panel below the manufacturer- or code-permitted thickness, and escalate per the Failure Points section.

I. Correct Concrete-Substrate Irregularities

1. For concrete, use approved grinding or scarifying only after hazardous-material and silica controls are established. Confirm wet-cutting, local extraction, HEPA vacuuming, and respiratory protection are in place before starting.
2. Vacuum all dust with HEPA equipment. Clear the corrected area completely before priming.

J. Prime and Apply Patch or Leveling Compound

1. Apply primer where required by the patch product. Follow the manufacturer's stated coverage rate and drying time before mixing patch.
2. Mix floor patch or leveling material using the specified water ratio and mixing time. Record the product name and batch on the Flatness Correction Record.
3. Apply patch within its working time. Spread and screed to the depth marked from the flatness survey.
4. Feather edges only where the product permits it. Confirm the manufacturer's instructions allow feathering before tapering any edge.
5. Do not use patch to bridge active cracks, movement joints, unsupported seams, or structural deflection. Stop and escalate per the Failure Points section if any such condition is found beneath a marked low area.

K. Cure, Reverify, and Release

1. Protect the repair through the specified cure time. Restrict traffic, moisture exposure, and further application until the manufacturer's stated cure period has elapsed.
2. Recheck flatness with the same measuring method. Use the same straightedge length at the same marked points recorded in Step G.
3. Mark remaining deficiencies. Identify any point that still exceeds the manufacturer's tolerance after the first correction.
4. Apply additional compatible correction only after the prior layer permits it. Confirm the manufacturer's recoat or build-up instructions before adding a second application.
5. Confirm transitions and finished-floor height. Recheck the finished-floor height at each transition point identified in Project 01 against the corrected surface.
6. Document product, batch, application depth, cure, and final flatness readings. Complete the Flatness Correction Record before releasing the area to Project 05.